Speedometer-testing machine



Nc v. 25, 1930. E. E. TOWNSEND i 8 SPEEDOMETER TESTING MACHINE Filed. July 18, 1928 N VEN TOR. 6% am JM X, f

TTORNEYS.

Patented Nov. 25 1930 1 UNITED STATES PATENT-OFFICE 1 pplication filed July 18, 1923. sa-151116. 293,698. ating this motor118 t -1na'y be driven at various speeds. 1 I.

This invention relatesto devices for test-; ing speedomete-rs. a

It is the principal object of the present in vention to provide a simple and inexpensive. 5 device for accurately testing automobile speedometers and their driving connections medium of gears2l. The ratiobetween these to determine their accuracy under the condigears is such that the master speedometer tions in which they normally operate. will be operated to indicate the. peripheral p In carryingout this object into practice, I. speed of, the rollers 14. innmile'sper hour. w 10 provide a master speedometer connected with which is fitted with} a-flexihle drive shaft :20.

: transmission :shaft 1 i i 1 A master speedometer e319 .is provided 1 This latter is driven byes shaft 11 thru aims Therefore, when the,rollers engage the l.

, an automobile.

the tracksis a a driving medium. This latter is drivenby ,the wheels of the automobile containing the speedometer to be tested. This permits the twospeedometers to operate in unison and enables the readingsthereof to be compared.

One form which the invention may assume is exemplified in the following description and illustrated by way of example in the accompanying drawings, in which:

1g. 1 is a View in plan of a device embodying the preferred form of myinvention;

Fig. 2 is a side elevation of the same.

Referring more particularly to the accompanying drawings, 10-indicates a pair of 1 tracks having a gauge equal to the tread of Arranged transversely of ings. Each of these shafts is fitted with a pair of rollers 14 interposed in the tracks which are cut away so thatanautomobile may be drivenupon the tracks and either the front or rear wheels thereof arranged on the rollers 14. The shafts 11 and 12 are so arranged that adjacent rollers of eachvpair Willalign with a track and will be disposed closely adjacent so thatwheels bearing on the rollerswill have driving contact with all ofthem.

The transmission shaft'is fitted with a gear disconnecting it from the shaft 12.

t Y The gear 15 is in mesh with a; pinion 17 keyed orotherwlse secured on the shaftof a variablespeed electric motor 18. By opermaster speedometer drive if desired. shaft 11 and a transmission shaft 12 which are arrangedat a spaced distance apart in parallelism and journalled in suitablebeargear 15 to or;

wheels of an automobile andaregdriven si multaneously with these wheels, the readings of both the speedometerinthe carand the master speedometer 1 should correspond.

Likewise, the distance -readings-on both T ,speedometers should be exactly In operation ofthe device the automobile containing the speedometer tojbe tested is driven on the tracks and its wheels arranged on the rollers. If theautomobile speedom-H the same.

eter is driven from theffront wheels of the In order that the wheels will ,bear withproper pressure on the rollers 14, I provide If the speedometer is driven froi'njltlie front'wheels ofjthe car itis necessary to drive these'wheels to testthe speedometer:

car, these wheels are arranged onthe rollers.

hydraulicorotherjacks 22 between thetmcks. V to re ieve a portion of theweightofthe car 1 .This is accomplished by placing-the'motor18.

in op'eration and c lutchingjthe-gehr 15 to the transmission shaft causing a driVe tobe "transmittedlto the rollers 14 o n the transmission shaft; As these rollers are in driving contact with the automobile wheels, thelatter will bedriven and will in turn d'riveithe. rollers on the speedometer drive shaft causing operation of the masterspeedometer. As

f the. linear speed of the rollers andjautomobile wheels will be the same'the readings offth'e two speedometer-s should correspond; Ifthey 1 do not, fthe' 'one in the car isadju-sted until accuratefl Itoftenoccursthat a speedometer will in- For this reason I dicate the road speed correctly atsome'speeds but incorrectly at others. I provide a variable speed motor in order that the speedometer may be tested atfall speeds. i If the speedometer is driven tremthe drive shaft of the car, the rear wheels of the car are arranged on the rollers 14. The eng ne of the car is placed in operation and a drlving connection established between the engine and the rear wheels to drive the latter. These wheels transmit a drive to the rollers 14 on the speedometer drive shaft to operate the master speedometer. A test is then conducted at various speeds to compare the readings of the speedometer-s. \Vhen the rear wheels of a car are on the rollers 14, the gear 15 is disconnected from the shaft 12 so that rollers 14 on this latter shaft will merely idle.

After the test has been conducted the car speedometer is properly adjusted and the car removed from the tracks.

From the foregoing, it is obvious that by means of my improved device a speedometer in an automobile maybe tested under ordinary road conditions. Further, this test enables the speedometer readings to be compared with that of an accurate speedometer driven simultaneous therewith and without disconnecting the speedometer being tested from its driving mechanism. This insures that both the speedometer and its driving mechanism Will be tested and any inaccuracies therein discovered.

\Vhile I have disclosed the preferred embodiment of my invention, it is to be understood that various changes may be made therein without departing from the spirit of the invention as defined in the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is 1. A speedometer testing device comprising a master speedometer drive shaft adapted to beactuated solely by the wheels of an automobile, a transmission shaft spaced from and arranged in parallelism with the said drive shaft and cooperating therewith to support a pair of wheels of an automobile, a master speedometer geared to the drive shaft, a n1otor, and means for connecting the motor with and disconnecting the motor from the transmission shaft to enable the said wheels of the automobile to be actuated either by the said motor or by the motor of the automobile.

2. A speedometer testing device including a master speedometer drive shaft provided with a pair of rollers, a master speedometer, gearing connecting the master speedometer with the said drive shaft, a transmission shaft spaced from the drive shaft and provided with a pair of rollers cooperating with the rollers of the drive shaft to support the wheels of an automobile, the said. drive shaft being actuated solely through contact with the said automobile wheels, a motor, gearing for communicating motion from the motor to the transmission shaft, and a clutch for 

